1) Field of the Invention
The present invention relates to a virtualized-information management apparatus that manages corresponding information between real volume(s) (real storage areas) of plural storages connected to a network and a virtual volume (virtual storage area) created by virtually integrating the real volume(s) (real storage areas), and that efficiently builds a virtualizing storage system with reliability.
2) Description of the Related Art
A technique of a storage area network (SAN) configured by connecting a plurality of storages such as a disk array drive and a tape drive via a network provides storage with large capacity to users. Recently, a virtualizing technique, where real volumes of the storages connected with the SAN are utilized as one virtual volume, has been applied to the SAN technique.
In such a virtualizing technique, mapping information between sectors of the real volumes of the storages and sectors of the virtual volume created virtually as one storage device is created, and the input/output (I/O) process is executed based on the mapping information.
The mapping information is stored in a management server connected with the SAN, and centrally managed by the management server. Therefore, when a malfunctioning occurs in the management server, access to data stored in the real volumes is impossible.
Japanese Patent Application Laid-Open No. 2002-91706 discloses a technique in which a plurality of mapping agents keep the mapping information in volatile memories, and a controller that manages the mapping information updates and backs up the mapping information held by the mapping agents.
In this system, even if a certain mapping agent malfunctions, the controller transmits correct mapping information to the mapping agent to recover it to a normal state.
However, since the controller centrally manages the mapping information held in the mapping agents, when any abnormality occurs in the controller itself, the mapping information cannot be properly managed.
Particularly, when an IP-SAN, which is a network where a plurality of SANs are connected via an Internet protocol (IP) network, is built, if a failure occurs in the controller, this affects management of all the SANs.
Even if the controller has no failure, when a failure occurs in the network that connects the controller, transmission/reception of data between the controller and the mapping agents cannot be executed. For this reason, the mapping information in all the mapping agents cannot be managed.